Heat exchange apparatus and heat pump apparatus

ABSTRACT

A heat exchange apparatus according to the present disclosure includes a refrigerant supply source, an ejector, an extractor, a first pump, a second pump, a cooler, and a liquid passage. The first pump is a dynamic pump and disposed on the liquid passage between the extractor and the cooler. The second pump is a positive displacement pump and disposed on the liquid passage between an outlet of the first pump and an inlet of refrigerant liquid of the ejector.

BACKGROUND

1. Technical Field

The present disclosure relates to a heat exchange apparatus and a heatpump apparatus.

2. Description of the Related Art

Conventional heat exchange apparatus has been used for refrigerationcycle apparatus applied to equipment such as an air conditioner, arefrigerator freezer, and a water heater. Japanese Patent No. 4454456describes a refrigeration cycle apparatus using water as a refrigeranthaving an extremely small load on the global environment. FIG. 6illustrates a refrigeration cycle apparatus described in Japanese PatentNo. 4454456.

As illustrated in FIG. 6, a refrigeration cycle apparatus 100 includesan evaporator 110, a condenser 120, a connection pipe 130, and aconnection pipe 150. An upper portion of the evaporator 110 is connectedto an upper portion of the condenser 120 by the connection pipe 130. Theconnection pipe 130 is provided with a compressor 140. A lower portionof the evaporator 110 is connected to a lower portion of the condenser120 by the connection pipe 150. The evaporator 110 is connected to anevaporator-side liquid passage 160. The evaporator-side liquid passage160 is provided with a load 180 and a cold water pump 220. The condenser120 is connected to a condenser-side liquid passage 170. Thecondenser-side liquid passage 170 is provided with a cooling tower 210and a coolant pump 230.

SUMMARY

In one general aspect, the techniques disclosed here feature a heatexchange apparatus including: a refrigerant supply source that suppliesa refrigerant vapor, the refrigerant vapor being a refrigerant in avapor phase; a cooler that cools a refrigerant liquid and that suppliesthe cooled refrigerant liquid, the refrigerant liquid being therefrigerant in a liquid phase; an ejector that produces a refrigerantmixed flow using the refrigerant vapor supplied from the refrigerantsupply source and the cooled refrigerant liquid supplied from thecooler; an extractor that receives the refrigerant mixed flow from theejector and extracts the refrigerant liquid from the refrigerant mixedflow; a liquid passage that constitutes a loop on which the extractor,the cooler and the ejector are disposed in this order and thatcirculates the refrigerant liquid flowing therein; a first pump that isa dynamic pump, that is disposed on the liquid passage between the anoutlet of the extractor and an inlet of the cooler, and that pumps theliquid refrigerant from the extractor to the cooler; and a second pumpthat is a positive displacement pump and that is disposed on the liquidpassage between an outlet of the first pump and an inlet of the ejector.

With the technique described above, a height from the first pump(dynamic pump) to the extractor can be reduced so that the size of theheat exchange apparatus can be reduced. Thus, performance of the heatexchange apparatus can be reduced with a suppressed increase in the sizeof the heat exchange apparatus.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a configuration of a heat exchange apparatusaccording to a first embodiment;

FIG. 2 is a sectional view of an ejector;

FIG. 3 illustrates a configuration of a heat exchange apparatusaccording to a second embodiment;

FIG. 4 illustrates a configuration of a heat exchange apparatusaccording to a third embodiment;

FIG. 5 illustrates a configuration of a heat exchange apparatusaccording to a fourth embodiment; and

FIG. 6 illustrates a configuration of a conventional refrigeration cycleapparatus.

DETAILED DESCRIPTION (Underlying Knowledge Forming Basis of the PresentDisclosure)

With an increased awareness of environments such as global warming,further enhancement of performance has been required for a heat exchangeapparatus or a heat pump apparatus. However, a technique for enhancingperformance of the heat exchange apparatus or the heat pump apparatusoften causes an increase in size of a system.

To enhance performance of a heat exchange apparatus or a heat pumpapparatus, a technique for efficiency increasing the pressure ofrefrigerant is needed. In view of this, inventors of the presentinvention have developed a technique of replacing a condenser with acondensation ejector and an extractor, as a technique for efficiencyincreasing the pressure of refrigerant. The extractor extracts onlyrefrigerant liquid from a refrigerant flow in two phases discharged fromthe condensation ejector. The pressure of refrigerant discharged fromthe compressor is efficiently increased with the condensation ejector sothat the refrigerant is condensed, thereby reducing work on thecompressor. Accordingly, a coefficient of performance (COP) of a systemcan be enhanced.

However, the inventors found that a system employing the above-describedtechnique requires a pump discharge pressure ten times as high as thatof a conventional system. That is, to enhance the COP of a system, apressure increase efficiency obtained by a pump and an ejector needs toexceed a pressure increase efficiency of a compressor. However, toincrease the pump discharge pressure while maintaining a high pumpefficiency, the head required for suppressing cavitation of the pump(required net positive suction head: NPSHr) significantly increases. Ifthe required pump discharge pressure decuples, the required net positivesuction head also decuples. This NPSHr needs to be obtained with aheight (water-level head) from the inlet of the pump to an internalliquid level of the extractor. In the conventional refrigeration cycleapparatus described in Japanese Patent No. 4454456, for example, awater-level head of 1 m is obtained. In the conventional refrigerationcycle apparatus described in Japanese Patent No. 4454456, in a casewhere the condenser 120 is replaced with an ejector and an extractor, awater-level head of 10 m is required. This causes an increase in size ofthe system.

As described above, the inventors of the present invention founddifficulty, as a new problem, in obtaining both maintenance of a highpump efficiency and prevention of a system size increase in fabricatinga heat exchange apparatus in which a condenser is replaced with acondensation ejector and an extractor and a refrigerant vapor from arefrigerant supply source is efficiently increased in pressure andcondensed by pump power. Based on the finding of the new problem, theinventors have reached the following aspects of the invention.

In a first aspect of the present disclosure, a heat exchange apparatusincludes:

a refrigerant supply source that supplies a refrigerant vapor, therefrigerant vapor being a refrigerant in a vapor phase;

a cooler that cools a refrigerant liquid and that supplies the cooledrefrigerant liquid, the refrigerant liquid being the refrigerant in aliquid phase;

an ejector that produces a refrigerant mixed flow using the refrigerantvapor supplied from the refrigerant supply source and the cooledrefrigerant liquid supplied from the cooler;

an extractor that receives the refrigerant mixed flow from the ejectorand extracts the refrigerant liquid from the refrigerant mixed flow;

a liquid passage that constitutes a loop on which the extractor, thecooler and the ejector are disposed in this order and that circulatesthe refrigerant liquid flowing therein;

a first pump that is a dynamic pump, that is disposed on the liquidpassage between the an outlet of the extractor and an inlet of thecooler, and that pumps the liquid refrigerant from the extractor to thecooler; and

a second pump that is a positive displacement pump and that is disposedon the liquid passage between an outlet of the first pump and an inletof the ejector.

In the first aspect, a width of pressure increase (a pump up width orrange) by the first pump can be set at a width corresponding to theNPSHr of the second pump. Since the NPSHr of the second pump issufficiently smaller than a required pressure of the ejector, the widthof pressure increase required for the first pump is small, and the NPSHrof the first pump is also small. Thus, the use of a dynamic pump as thefirst pump can efficiently increase the pressure with a small NPSHr. Inaddition, the second pump sucks refrigerant liquid whose pressure hasbeen increased in a width corresponding to the NPSHr of the second pump,and thus, the risk of performance degradation due to cavitation in thesecond pump can be reduced. Accordingly, the pressure of an efficientpositive displacement pump as the second pump can efficiently increasethe pressure of refrigerant liquid to a required pressure of theejector. Thus, in this configuration, the height from the first pump tothe extractor is reduced so that the size of the heat exchange apparatuscan be reduced and the pressure of refrigerant liquid can be efficientlyincreased to a required pressure of the ejector.

In a second aspect of the present disclosure, the heat exchangeapparatus in the first aspect may further include: a third pump that isa dynamic pump and that is disposed on the liquid passage between theoutlet of the first pump and an inlet of the second pump. In the secondaspect, the width of pressure increase by the first pump can be furtherreduced so that the NPSHr of the first pump can be further reduced andthe size of the heat exchange apparatus can be further reduced.

In a third aspect of the present disclosure, the second pump of the heatexchange apparatus of the first or second aspect may be disposed on theliquid passage between the outlet of the first pump and an inlet of thecooler.

In a fourth aspect of the present disclosure, the first pump of the heatexchange apparatus in one of the first to third aspects may be locatedat a lowest level in a vertical direction on the liquid passage.

In a fifth aspect of the present disclosure, the first pump and thesecond pump of the heat exchange apparatus in one of the first to fourthaspects may be located at an identical level in a vertical direction.

In a sixth aspect of the present disclosure, in the heat exchangeapparatus in one of the first to fifth aspects, the first pump may havea required net positive suction head smaller than a required netpositive suction head of the second pump, and the first pump may have awidth of pressure increase larger than the required net positive suctionhead of the second pump.

In a seventh aspect of the present disclosure, the second pump of theheat exchange apparatus in one of the first to sixth aspects may have apump efficiency higher than a pump efficiency of the first pump. Thephrase of “the second pump has a pump efficiency higher than a pumpefficiency of the first pump” means that the maximum efficiency of thesecond pump is higher than the maximum efficiency of the first pump.

In an eighth aspect of the present disclosure, a saturation vaporpressure at a temperature of 20° C.±15° C. of the refrigerant of theheat exchange apparatus in one of the first to seventh aspects may belower than an atmospheric pressure.

A heat pump apparatus in a ninth aspect of the present disclosureincludes the heat exchange apparatus according to any one of the firstto eighth aspects, and the refrigerant supply source is a compressorthat compresses a refrigerant vapor input to the refrigerant supplysource and that outputs the compressed refrigerant vapor to the ejector.In the ninth aspect, advantages as those of the first aspect can beobtained.

In a tenth aspect of the present disclosure, the heat pump apparatus inthe ninth aspect may further include an evaporator that generates therefrigerant vapor to be supplied to the compressor; and a liquid backpassage that connects the extractor and the evaporator and that flows arefrigerant liquid that has an amount equal to the refrigerant that wasoutput from the evaporator and that was supplied to the extractor viathe compressor and the ejector. With the configuration in which theamount of the refrigerant liquid in the evaporator and the amount of therefrigerant liquid in the extractor are balanced by the liquid backpassage, the heat pump apparatus can be stably operated.

Embodiments of the present disclosure will be described hereinafter withreference to the drawings. The present disclosure is not limited to thefollowing embodiments.

FIRST EMBODIMENT

As illustrated in FIG. 1, a heat exchange apparatus 200 according to afirst embodiment includes a refrigerant supply source 11, an ejector 12,an extractor 13, a first pump 14, a second pump 15, a cooler 16, and afirst liquid passage 17. The first liquid passage 17 constitutes a loopand includes pipes 17 a to 17 e. On the loop constituted by the firstliquid passage 17, the ejector 12, the extractor 13, the first pump 14,the second pump 15, and the cooler 16 are connected to one another inthis order by the pipes 17 a to 17 e.

The refrigerant supply source 11 is not specifically limited as long asthe refrigerant supply source 11 can supply a refrigerant vapor (arefrigerant in a gas phase) to the ejector 12. The refrigerant supplysource 11 is, for example, a compressor that is a component of a heatpump apparatus. The refrigerant supply source 11 may be an evaporatorthat vaporizes a refrigerant (e.g., water) by using exhaust heat fromfactories and outputs the vaporized refrigerant as a refrigerant vapor.

As illustrated in FIG. 2, the ejector 12 includes a first nozzle 23, asecond nozzle 25, a mixing portion 27, and a diffuser portion 28. Thefirst nozzle 23 is connected to the cooler 16 by the pipe 17 e. Therefrigerant liquid (refrigerant in a liquid phase) flowed from thecooler 16 is supplied as a motive flow to the first nozzle 23 throughthe pipe 17 e. The second nozzle 25 is connected to the refrigerantsupply source 11 by the pipe 26 b (vapor passage). The temperature ofliquid refrigerant ejected from the first nozzle 23 is reduced by thecooler 16. The refrigerant liquid ejected from the first nozzle 23 withacceleration and the expanded refrigerant vapor ejected from the secondnozzle 25 with acceleration are mixed in the mixing portion 27. Then,there occur first condensation due to a temperature difference betweenthe refrigerant liquid and the refrigerant vapor and second condensationdue to a pressure increase based on energy transportation between therefrigerant liquid and the refrigerant vapor and momentum transportationbetween the refrigerant liquid and the refrigerant vapor. Therefrigerant vapor supplied from the refrigerant supply source 11 iscontinuously sucked into the second nozzle 25 through the pipe 26 b.Through the two condensation stages, a refrigerant mixed flow having asmall quality (dryness fraction) is generated. The diffuser portion 28restores a static pressure by decelerating the refrigerant mixed flow.In the ejector 12 having such a configuration, the temperature andpressure of refrigerant increase.

The ejector 12 includes a needle pipe 29 and a servo actuator 30. Theneedle pipe 29 and the servo actuator 30 are flow controllers forcontrolling the flow rate of refrigerant liquid as a motive flow. Thecross section of the orifice of the first nozzle 23 at a tip thereof canbe changed by using the needle pipe 29. The servo actuator 30 can adjustthe location of the needle pipe 29. With this configuration, the flowrate of the refrigerant liquid flowing in the first nozzle 23 can becontrolled.

The extractor 13 receives the refrigerant mixed flow from the ejector12, extracts refrigerant liquid from the refrigerant mixed flow, andstores the refrigerant liquid. That is, the extractor 13 separates therefrigerant liquid and the refrigerant vapor from each other. Theextractor 13 basically extracts only the refrigerant liquid. Theextractor 13 is, for example, a pressure-resistant container having heatinsulating properties. The configuration of the extractor 13 is notspecifically limited as long as the extractor 13 can extract refrigerantliquid.

The first liquid passage 17 is a passage through which refrigerantliquid flowed from the extractor 13 returns to the extractor 13 via thecooler 16 and the ejector 12. The first passage 17 constitutes a loop.On the first passage 17, the extractor 13, the cooler 16, and theejector 12 are arranged in this order. The refrigerant liquid circulatesin the first passage 17.

The first pump 14 is disposed on the first liquid passage 17 between theextractor 13 and the cooler 16 (specifically between an outlet of theextractor 13 and an inlet of the cooler 16). The first pump 14 pumps therefrigerant liquid received from the extractor 13 to the cooler 16.

In the first embodiment, the first pump 14 is a dynamic pump. Thedynamic pump is a pump that gives a speed to received fluid (refrigerantliquid), increases the pressure thereof by performing static pressurerecovery on the given speed, and sends the fluid. Examples of thedynamic pump include a centrifugal pump, a diagonal pump, and an axialflow pump. The first pump 14 is disposed at a location at which a heightH from an inlet of the first pump 14 to the liquid level of refrigerantliquid in the extractor 13 is larger than the NPSHr of the first pump14.

The second pump 15 is disposed on the first liquid passage 17 between anoutlet of the first pump 14 to a liquid inlet (inlet of refrigerantliquid, inlet of a motive flow) of the ejector 12. In the firstembodiment, the second pump 15 is disposed on the first liquid passage17 between the outlet of the first pump 14 and the inlet of the cooler16. In a case where the second pump 15 is disposed at such a location, apressure loss in a section between the outlet of the first pump 14 andan inlet of the second pump 15 can be minimized. Consequently, thepossibility of cavitation in the second pump 15 further decreases. Inaddition, the possibility that the second pump 15 sucks a refrigerant ina gas phase in a period of transition such as a start time alsodecreases. Alternatively, the second pump 15 may be disposed on thefirst liquid passage 17 between an outlet of the cooler 16 and theliquid inlet of the ejector 12. That is, the second pump 15 may bedisposed downstream of the cooler 16.

In the first embodiment, the second pump 15 is a positive displacementpump. The positive displacement pump is a pump that increases thepressure of received fluid (refrigerant liquid) by changing the volumethereof and sends the fluid. Examples of the positive displacement pumpinclude a piston pump, a plunger pump, a gear pump, a roots pump, a vanepump, and a rotary pump.

In the first embodiment, the first pump 14 is located at a lowest levelin a vertical direction in the first liquid passage 17. The positionalrelationship between the first pump 14 and the second pump 15 in thevertical direction is not specifically limited. However, the second pump15 and the first pump 14 are preferably disposed at an identical levelin the vertical direction.

In the first embodiment, in the first pump 14, the pressure ofrefrigerant liquid is increased to a pressure at which the second pump15 does not cause cavitation. A most important performance required forthe first pump 14 is unlikeliness of cavitation with a small NPSHr. Thatis, a dynamic pump is more preferably used as the first pump 14 than apositive displacement pump is. The dynamic pump has difficulty inincreasing the pressure of refrigerant liquid to a high pressure but isnot likely to cause cavitation with a small NPSHr. On the other hand,most important performances for the second pump 15 are high efficiencyand capability of increasing the pressure of refrigerant liquid to ahigh pressure. That is, a positive displacement pump is more preferablyused as the second pump 15 than a dynamic pump is. The NPSHr of thefirst pump 14 is smaller than the NPSHr of the second pump 15. The ratioof (NPSHr of first pump 14)/(NPSHr of second pump 15) is about 0.1, forexample.

The cooler 16 is constituted by a known heat exchanger such as afin-and-tube heat exchanger, a shell-and-tube heat exchanger, and acooling tower.

An operation of the heat exchange apparatus 200 will now be described.

First, the ejector 12 receives a refrigerant vapor discharged from therefrigerant supply source 11 and a refrigerant liquid supplied from thecooler 16 and generates a refrigerant mixed flow. The refrigerant mixedflow generated by the ejector 12 is input to the extractor 13. Theextractor 13 extracts refrigerant liquid and stores the refrigerantliquid therein. The refrigerant liquid stored in the extractor 13 issupplied to the ejector 12 via the first pump 14, the second pump 15,and the cooler 16. To reduce a loss of an effective head by a pressureloss of the pipe, the first pump 14 is disposed on the first liquidpassage 17 between the outlet of the extractor 13 and the inlet of thecooler 16. The refrigerant liquid stored in the extractor 13 is firstsucked into the first pump 14 and is then increased in pressure in thefirst pump 14. The pressure of the refrigerant liquid that has beenincreased by the first pump 14 is further increased by the second pump15 disposed on the first liquid passage 17 between the outlet of thefirst pump 14 and the liquid inlet of the ejector 12. The second pump 15may be disposed on the first liquid passage 17 between the outlet of thecooler 16 and the liquid inlet of the ejector 12.

In the first embodiment, the pressure of the refrigerant liquidextracted by the extractor 13 is increased by the first pump 14 and thenis further increased by the second pump 15. The width of the pressureincrease by the first pump 14 can be set at a width corresponding to theNPSHr of the second pump 15. Since the NPSHr of the second pump 15 issufficiently smaller than a required pressure of the ejector 12, arequired width of pressure increase by the first pump 14 is small, andthe NPSHr of the first pump 14 is also small. Thus, the use of thedynamic pump as the first pump 14 can efficiently increase the pressurewith a small NPSHr. In addition, since the second pump 15 sucksrefrigerant liquid whose pressure has been increased in a widthcorresponding to the NPSHr of the second pump 15, the risk ofperformance degradation due to cavitation in the second pump 15 can bereduced. Thus, the use of an efficient positive displacement pump as thesecond pump 15 can efficiently increase refrigerant liquid to a requiredpressure of the ejector 12. Accordingly, in the first embodiment, theheight from the first pump 14 to the extractor 13 is reduced so that thesize of the heat exchange apparatus 200 can be reduced and the pressureof refrigerant liquid can be efficiently increased to a requiredpressure of the ejector 12.

SECOND EMBODIMENT

As illustrated in FIG. 3, a heat exchange apparatus 300 according to asecond embodiment additionally includes a third pump 18 in addition tothe configuration of the heat exchange apparatus 200 described withreference to FIG. 1. In the second embodiment, a first liquid passage 17constitutes a loop and includes pipes 17 a to 17 f. On the loopconstituted by the first liquid passage 17, the ejector 12, theextractor 13, the first pump 14, the third pump 18, the cooler 16, andthe second pump 15 are connected to one another in this order by thepipes 17 a to 17 f.

The third pump 18 is disposed on the first liquid passage 17 between thefirst pump 14 and the second pump 15. Specifically, the third pump 18 isdisposed on the first liquid passage 17 between the outlet of the firstpump 14 and the inlet of the second pump 15. More specifically, thethird pump 18 is disposed on the first liquid passage 17 between theoutlet of the first pump 14 and the inlet of the cooler 16. The thirdpump 18 is a dynamic pump. One or more pumps may be additionallyprovided on the first liquid passage 17 between the first pump 14 andthe second pump 15. That is, on the first liquid passage 17 between theoutlet of the first pump 14 and the inlet of the second pump 15, aplurality of pumps including the third pump 18 to an N-th pump (where Nis an integer of four or more) may be disposed in this order in a flowdirection of refrigerant liquid. These pumps can be dynamic pumps.

In the heat exchange apparatus 300, the second pump 15 is disposedbetween the outlet of the cooler 16 and the liquid inlet of the ejector12. The second pump 15 may be disposed between the outlet of the N-thpump and the inlet of the cooler 16. That is, the third pump 18 and theadditional pumps can be disposed between the outlet of the first pump 14and the inlet of the second pump 15, independently of the location ofthe cooler 16.

In the second embodiment, the plurality of dynamic pumps are disposed onthe first liquid passage 17. Such multiple stages of dynamic pumpsindividually provide speeds to fluid (refrigerant liquid) passingthrough the pumps. Thus, the efficiency of the entire multi-stagedynamic pumps can be significantly increased, as compared to a casewhere a single dynamic pump is provided. The total NPSHr of the dynamicpumps is smaller than the NPSHr of the second pump 15. The ratio of(total NPSHr of dynamic pumps)/(NPSHr of second pump 15) is less than orequal to 0.1, for example.

In the second embodiment, the width of the pressure increase by thefirst pump 14 can be further reduced so that the NPSHr of the first pump14 can be further reduced, resulting in further size reduction of theheat exchange apparatus 300.

(Variations)

The heat exchange apparatus 200 illustrated in FIG. 1 and the heatexchange apparatus 300 illustrated in FIG. 3 may be charged domesticwith a refrigerant whose saturation vapor pressure is negative (lowerthan atmospheric pressure in an absolute pressure) at an ordinarytemperature (Japanese Industrial Standards: 20° C±15° C./JIS Z8703).Examples of such a refrigerant include a refrigerant including wateralcohol, or ether as a main component. In an operation of the heatexchange apparatus 200 or 300, the internal pressure of the heatexchange apparatus 200 or 300 is lower than the atmospheric pressure.The pressure at the outlet of the refrigerant supply source 11 is in therange from 5 to 15 kPaA, for example. To prevent freezing, for example,the refrigerant may be a refrigerant containing water as a maincomponent and includes 10 to 40%, in terms of mass %, of ethyleneglycol, Nybrine (registered trademark), or mineral salts, for example.The “main component” herein refers to a component occupying the largestproportion in mass ratio. In a case where the heat exchange apparatus200 or 300 is charged with such a refrigerant, the size of the systemtends to increase, as compared to a case where an apparatus is chargedwith a refrigerant whose pressure saturation vapor pressure at anordinary temperature is positive. Thus, the technique disclosed hereinis significantly effective for a system using a refrigerant whosesaturation vapor pressure at an ordinary temperature is negative.

THIRD EMBODIMENT

FIG. 4 illustrates a configuration of a heat pump apparatus according toa third embodiment. A heat pump apparatus 400 (refrigeration cycleapparatus) according to the third embodiment includes a first heatexchange unit 40, a second heat exchange unit 42, a compressor 31, and avapor passage 26. The first heat exchange unit 40 and the second heatexchange unit 42 form a heat-dissipation side circuit and aheat-absorption side circuit, respectively. Refrigerant vapor generatedby the second heat exchange unit 42 is supplied to the first heatexchange unit 40 via the compressor 31 and the vapor passage 26.

The compressor 31, a downstream portion 26 b of the vapor passage 26,and the first heat exchange unit 40 correspond to the heat exchangeapparatus 200 described with reference to FIG. 1. That is, the heat pumpapparatus 400 includes the heat exchange apparatus 200. The compressor31 corresponds to the refrigerant supply source 11, compresses receivedrefrigerant vapor, and outputs the compressed refrigerant vapor to theejector 12. Thus, the heat pump apparatus 400 can obtain advantagessimilar to those of the first embodiment.

Description similar to that of the heat exchange apparatus 200 in thefirst embodiment is applicable to the first heat exchange unit 40.

The second heat exchange unit 42 includes an evaporator 19, a pump 20(evaporator-side pump), and a heat exchanger 21. The evaporator 19stores refrigerant liquid and vaporizes the refrigerant liquid, therebygenerating a refrigerant vapor to be compressed in the compressor 31.The evaporator 19, the pump 20, and the heat exchanger 21 are connectedto one another by pipes 22 a to 22 c to constitute a loop. Theevaporator 19 is constituted by, for example, a pressure-resistantcontainer having heat insulating properties. The pipes 22 a to 22 cconstitute a second liquid passage 22 in which refrigerant liquid storedin the evaporator 19 circulates via the heat exchanger 21. The pump 20is provided on the second liquid passage 22 between a liquid outlet ofthe evaporator 19 and an inlet of the heat exchanger 21. The pump 20increases the pressure of the refrigerant liquid stored in theevaporator 19 and pumps the refrigerant liquid to the heat exchanger 21.The discharge pressure of the pump 20 is lower than the atmosphericpressure. The pump 20 is disposed at a location at which a height Hefrom an inlet of the pump 20 to the liquid level of refrigerant liquidin the evaporator 19 is larger than a required head (NPSHr).

The heat exchanger 21 is constituted by a known heat exchanger such as afin-and-tube heat exchanger or a shell-and-tube heat exchanger.

In the third embodiment, the evaporator 19 is a heat exchanger thatdirectly vaporizes, therein, refrigerant liquid heated by circulating inthe second liquid passage 22. The refrigerant liquid stored in theevaporator 19 is in direct contact with refrigerant liquid circulatingin the second liquid passage 22. That is, part of the refrigerant liquidin the evaporator 19 is heated by the heat exchanger 21 and is used as aheat source for heating refrigerant liquid in a saturation state. Anupstream end of the pipe 22 a is preferably connected to a lower portionof the evaporator 19. A downstream end of the pipe 22 c is preferablyconnected to an intermediate portion of the evaporator 19. The secondheat exchange unit 42 may be configured in such a manner thatrefrigerant liquid stored in the evaporator 19 is not mixed with otherrefrigerant liquid circulating in the second liquid passage 22. Forexample, in a case where the evaporator 19 has a heat exchangeconfiguration similar to that of a shell-and-tube heat exchanger,refrigerant liquid stored in the evaporator 19 can be heated andevaporated by a heating medium circulating in the second liquid passage22. In the heat exchanger 21, a heating medium for heating therefrigerant liquid stored in the evaporator 19 flows.

The vapor passage 26 includes an upstream portion 26 a and thedownstream portion 26 b. On the vapor passage 26, the compressor 31 isdisposed. An upper portion of the evaporator 19 is connected to an inletof the compressor 31 through the upstream portion 26 a of the vaporpassage 26. An outlet of the compressor 31 is connected to a secondnozzle 25 of the ejector 12 through the downstream portion 26 b of thevapor passage 26. The compressor 31 is a centrifugal compressor or apositive-displacement compressor. On the vapor passage 26, a pluralityof compressors may be provided. The compressor 31 sucks a refrigerantvapor from the evaporator 19 of the second heat exchange unit 42 throughthe upstream portion 26 a and compresses the refrigerant vapor. Thecompressed refrigerant vapor is supplied to the ejector 12 through thedownstream portion 26 b.

In the third embodiment, the temperature and pressure of refrigerant areincreased in the ejector 12. Since work on the compressor 31 can bereduced, the compression ratio of the compressor 31 can be significantlyreduced and the efficiency of the heat pump apparatus 400 can beincreased to a level equal or higher than that in a conventionaltechnique. In addition, the size of the heat pump apparatus 400 can bereduced.

The heat pump apparatus 400 further includes a liquid back passage 32(required-return pipe) for returning refrigerant from the first heatexchange unit 40 to the second heat exchange unit 42. In the thirdembodiment, the extractor 13 and the evaporator 19 are connected to eachother by the liquid back passage 32 so that refrigerant stored in theextractor 13 can be transferred to the evaporator 19. Typically, a lowerportion of the extractor 13 and a lower portion of the evaporator 19 areconnected to each other by the liquid back passage 32. The refrigerantliquid returns from the extractor 13 to the evaporator 19 through theliquid back passage 32. The liquid back passage 32 may be provided withan expansion mechanism such as a capillary or an expansion valve.

The liquid back passage 32 is disposed in such a manner that the liquidback passage 32 connects the extractor 13 and the evaporator 19 to eachother, refrigerant liquid having an amount equal to an amount (mass flowrate) of a refrigerant vapor transferred from the evaporator 19 to theextractor 13 by the compressor 31 returns from the extractor 13 to theevaporator 19. When the amount of refrigerant liquid in the evaporator19 and the amount of refrigerant liquid in the extractor 13 are balancedby the liquid back passage 32, the heat pump apparatus 400 can be stablyoperated. In a case where the amount of the refrigerant liquid stored inthe evaporator 19 and the extractor 13 is sufficiently larger than theamount of refrigerant vapor transferred by an operation of the heat pumpapparatus 400, the liquid back passage 32 may be omitted.

The liquid back passage 32 may be branched off at any location on thefirst heat exchange unit 40. For example, the liquid back passage 32 maybe branched off at the pipe 17 a connecting the ejector 12 and theextractor 13 to each other, or may be branched off at an upper portionof the extractor 13. The first heat exchange unit 40 may be configuredto discharge redundant refrigerant when necessary. The second heatexchange unit 42 may be configured to add refrigerant when necessary.

In a manner similar to that of the heat exchange apparatus 200, the heatpump apparatus 400 can use a refrigerant whose saturation vapor pressureat an ordinary temperature is negative.

FOURTH EMBODIMENT

FIG. 5 illustrates a configuration of a heat pump apparatus according toa fourth embodiment. A heat pump apparatus 500 (refrigeration cycleapparatus) according to the fifth embodiment includes a first heatexchange unit 41, a second heat exchange unit 42, a compressor 31, and avapor passage 26. The first heat exchange unit 41 and the second heatexchange unit 42 constitute a heat-dissipation side circuit and aheat-absorption side circuit, respectively. A refrigerant vaporgenerated in the second heat exchange unit 42 is supplied to the firstheat exchange unit 41 via the compressor 31 and the vapor passage 26.

The compressor 31, a downstream portion 26 b of the vapor passage 26,and the first heat exchange unit 41 correspond to the heat exchangeapparatus 300 described with reference to FIG. 3. That is, the heat pumpapparatus 500 includes a heat exchange apparatus 300. The compressor 31corresponds to a refrigerant supply source 11, compresses receivedrefrigerant vapor, and outputs the compressed refrigerant vapor to theejector 12. Thus, in the heat pump apparatus 500, advantages similar tothose described in the second embodiment can be obtained.

Description similar to that of the heat exchange apparatus 300 in thesecond embodiment is applicable to the first heat exchange unit 41.Detailed description of the second heat exchange unit 42 is similar tothat in the third embodiment.

In a manner similar to the heat exchange apparatus 300, the heat pumpapparatus 500 can use a refrigerant whose saturation vapor pressure atan ordinary temperature is negative.

As described above, a heat exchange apparatus and a heat pump apparatusdescribed herein includes a first pump 14 (dynamic pump) and a secondpump 15 (positive displacement pump). The width of pressure increase bythe first pump 14 is set equal to the width of pressure increasecorresponding to the NPSHr of the second pump 15. Since the NPSHr of thesecond pump 15 is sufficiently smaller than a required pressure of theejector 12, a required width of pressure increase by the first pump 14is also small, and the NPSHr of the first pump 14 is small. Thus, theheight from the first pump 14 to the extractor 13 can be reduced. Thatis, the height of the heat exchange apparatus or the heat pump apparatuscan be reduced so that the size of the entire system can be reduced.

The technique described herein can provide a small-size efficient heatpump apparatus. Specifically, air-conditioning can be performed by usinga heat pump apparatus 400 or 500 even in a building with a smallinstallation space. In addition to air-conditioning, hot water at highertemperatures can be supplied in application of the heat pump apparatus400 or 500 to hot water supply.

A heat exchange apparatus and a heat pump apparatus disclosed herein areapplicable to a hot water heating apparatus using vapor, airconditioners such as a domestic air-conditioner and a business-useair-conditioner, and a water heater, for example.

What is claimed is:
 1. A heat exchange apparatus comprising: arefrigerant supply source that supplies a refrigerant vapor, therefrigerant vapor being a refrigerant in a vapor phase; a cooler thatcools a refrigerant liquid and that supplies the cooled refrigerantliquid, the refrigerant liquid being the refrigerant in a liquid phase;an ejector that produces a refrigerant mixed flow using the refrigerantvapor supplied from the refrigerant supply source and the cooledrefrigerant liquid supplied from the cooler; an extractor that receivesthe refrigerant mixed flow from the ejector and extracts the refrigerantliquid from the refrigerant mixed flow; a liquid passage thatconstitutes a loop on which the extractor, the cooler and the ejectorare disposed in this order and that circulates the refrigerant liquidflowing therein; a first pump that is a dynamic pump, that is disposedon the liquid passage between the an outlet of the extractor and aninlet of the cooler, and that pumps the liquid refrigerant from theextractor to the cooler; and a second pump that is a positivedisplacement pump and that is disposed on the liquid passage between anoutlet of the first pump and an inlet of the ejector.
 2. The heatexchange apparatus according to claim 1, further comprising: a thirdpump that is a dynamic pump and that is disposed on the liquid passagebetween the outlet of the first pump and inlet of the second pump. 3.The heat exchange apparatus according to claim 1, wherein the secondpump is disposed on the liquid passage between the outlet of the firstpump and an inlet of the cooler.
 4. The heat exchange apparatusaccording to claim 1, wherein the first pump is located at a lowestlevel in a vertical direction on the liquid passage.
 5. The heatexchange apparatus according to claim 1, wherein the first pump and thesecond pump are located at an identical level in a vertical direction.6. The heat exchange apparatus according to claim 1, wherein the firstpump has a required net positive suction head smaller than a requirednet positive suction head of the second pump, and the first pump has awidth of pressure increase larger than the required net positive suctionhead of the second pump.
 7. The heat exchange apparatus according toclaim 1, wherein the second pump has a pump efficiency higher than apump efficiency of the first pump.
 8. The heat exchange apparatusaccording to claim 1, wherein a saturation vapor pressure at atemperature of 20° C±15° C. of the refrigerant is lower than anatmospheric pressure.
 9. A heat pump apparatus comprising: the heatexchange apparatus according to claim 1, wherein the refrigerant supplysource is a compressor that compresses a refrigerant vapor input to therefrigerant supply source and that outputs the compressed refrigerantvapor to the ejector.
 10. The heat pump apparatus according to claim 9,further comprising: an evaporator that generates the refrigerant vaporto be supplied to the compressor; and a liquid back passage thatconnects the extractor and the evaporator and that flows a refrigerantliquid that has an amount equal to the refrigerant that was output fromthe evaporator and that was supplied to the extractor via the compressorand the ejector.